I created a bill on 12/8/2020, for a fixed asset and it cleared 1/4/2021. Why does the asset not appear on the balance sheet at 12/31/2020

Thanks for being here with us today, tina32.

Let's look into the filters of the Balance Sheet report to make sure we get accurate information.

Try setting the reporting period to all All Dates option. You can also check if you choose the correct Accounting method when running the reports.

An accrual-basis report shows income regardless of whether your customers have paid your invoices and expenses or if you have paid all your bills. While a cash basis report only shows income if you have received or paid expenses in cash.

Below is a sample screenshot so you can have a better view:

Check out this article to know more about managing Balance Sheets in QBO: FAQ: Basic troubleshooting for balance sheets.

To become more familiar with customizing reports in QBO, feel free to visit this article: 

• How to Customize Reports: Basics, Sorting & Date Ranges
• Memorize reports in QuickBooks Online

The Community is always open if you have additional report inquiries or other questions about QuickBooks. I'll be around to help. Wishing you a great day ahead!